/Engine/Plugins/Experimental/Mutable/Source/MutableTools/Public/MuT/NodeScalarCurve.h
void SetKeyFrame ( int index, float time, float value, float in_tangent, float in_tangent_weight, float out_tangent, float out_tangent_weight, uint8_t interp_mode, uint8_t tangent_mode, uint8_t tangent_weight_mode )